To be honest, neither.
Samsung's 2020 QLED models have taken a step backwards in performance terms from the previous years models. They're just not as good. In addition, the entry-level QLED models (Q60T and Q65T) don't offer the same range of benefits as the higher-specified QLED ranges. They should really sit in a category of their own, somewhere between QLED and standard LCD/LED TV. In reality though, they're closer to everyone else's standard LCD/LED than Samsung would really like to admit.
This brings us to the bigger problem for Samsung: It's that the TU range is worse.
The whole TV market has taken a bit of a battering with the general world economic picture, and then Brexit, and now COVID. The consequence is that business costs are up, sales are down, and profits are in the toilet. Panasonic and Sony have been losing money in TV production for years. LG and Samsung have deeper corporate pockets, higher sales volumes, and better control of costs; so they're weathering the storm a little better, but they're still feeling the pain which is why this year's Samsung QLEDs have had features stripped compared to last year.
If it was my money I wouldn't tip £600 in to a 43" Q60T. It's just not good enough. But no one is making an outstanding 43" £600 TV to compare. They're all compromised in some way, be it refresh rate, viewing angle, screen brightness for HDR, processing power, a lack of local dimming etc etc. So then, my view would be that if I'm going to have to compromise, then I might as well save some money in the process.
Unless you're a serious serious gamer, I would look at the Philips 43PUS8555 @ £449. It's a better set than the TU8500, and it has a better specification than the Q60T as well, and all for £150 less. Get it from Richer Sounds with their 6-year warranty if applicable.
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